U.S. patent application number 12/178378 was filed with the patent office on 2010-01-28 for seal comprising elastomeric composition with nanoparticles.
This patent application is currently assigned to SMITH INTERNATIONAL, INC.. Invention is credited to Saman Chandana Nanayakkara.
Application Number | 20100018778 12/178378 |
Document ID | / |
Family ID | 41567633 |
Filed Date | 2010-01-28 |
United States Patent
Application |
20100018778 |
Kind Code |
A1 |
Nanayakkara; Saman
Chandana |
January 28, 2010 |
SEAL COMPRISING ELASTOMERIC COMPOSITION WITH NANOPARTICLES
Abstract
Seals and sealing members are formed from a composition
generally comprising a first elastomeric material and a second
elastomeric material, wherein the second elastomeric material
comprises a dispersion of nanosized particles disposed within a
polymer matrix of the second elastomeric material. Preferred first
and second elastomeric materials are fluoroelastomers, and
preferred nanosized particles are fluoropolymers. The nanosized
particles are sized less than about 100 nm. The composition
comprises about 0.2 to 65 percent by weight of first elastomeric
material, about 20 to 95 percent by weight of second elastomeric
material, and about 10 to 90 percent by weight particles based on
the total weight of the particles and the second elastomeric
material. The composition can be used to form annular O-ring seals
placed within rotary cone bits used for drilling subterranean
formations, and can be used to form a selected portion of the seal
or the entire seal.
Inventors: |
Nanayakkara; Saman Chandana;
(Rancho Cucamonga, CA) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ LLP
P.O. BOX 2207
WILMINGTON
DE
19899
US
|
Assignee: |
SMITH INTERNATIONAL, INC.
Houston
TX
|
Family ID: |
41567633 |
Appl. No.: |
12/178378 |
Filed: |
July 23, 2008 |
Current U.S.
Class: |
175/371 ;
277/322; 525/199; 525/233; 525/236 |
Current CPC
Class: |
C08L 21/00 20130101;
E21B 10/25 20130101; C08L 27/12 20130101; F16J 15/104 20130101;
C08K 3/38 20130101; F16J 15/102 20130101; C08K 3/346 20130101; C08L
21/00 20130101; C08L 2205/03 20130101; C08L 21/00 20130101; C08L
27/12 20130101; C08L 21/00 20130101; C08L 21/00 20130101; C08K
3/013 20180101; C08L 21/00 20130101; C08K 3/013 20180101; C08K
3/346 20130101; C08K 3/38 20130101; C08K 3/38 20130101; C08K 7/02
20130101; C08K 7/02 20130101; C08L 21/00 20130101; C08K 3/013
20180101; C08K 7/02 20130101; C08K 3/013 20180101; C08L 2666/04
20130101; C08L 2666/08 20130101; C08K 3/346 20130101; C08K 3/346
20130101; C08L 27/12 20130101; C08K 7/02 20130101; C08L 2666/04
20130101; C08K 3/38 20130101; C08K 3/013 20180101; C08K 3/38
20130101; C08K 3/346 20130101; C08L 21/00 20130101; C08L 27/12
20130101; C08K 7/02 20130101; C08L 21/00 20130101; C08K 3/04
20130101; C08L 2205/02 20130101 |
Class at
Publication: |
175/371 ;
277/322; 525/199; 525/233; 525/236 |
International
Class: |
E21B 10/25 20060101
E21B010/25; E21B 3/00 20060101 E21B003/00; C08L 27/12 20060101
C08L027/12; C08L 9/06 20060101 C08L009/06; C08L 9/00 20060101
C08L009/00 |
Claims
1. A composition for making a seal used in an oil production
operation, the composition comprising: a first elastomeric
material; and a second elastomeric material, wherein the second
elastomeric material comprises a dispersion of particles disposed
within a polymer matrix of the second elastomeric material, and
wherein the particles have an average size of less than about 100
nm.
2. The composition as recited in claim 1 wherein the particles have
an average particle size in the range of from about 30 to 80
nm.
3. The composition as recited in claim 1 wherein the particles have
an average particle size in the range of from about 35 to 55
nm.
4. The composition as recited in claim 1 wherein the second
elastomeric material and the particles are formed from the same
general family of polymeric materials.
5. The composition as recited in claim 4 wherein the first and
second elastomeric material are fluoropolymers.
6. The composition as recited in claim 1 wherein the second
elastomeric material is selected from the group of material
consisting of.fluoropolymers, fluoroelastomers, acrylonitrile
butadiene (nitrile) rubber, highly-saturated nitrile, hydrogenated
nitrile, hydrogenated carboxylated acrylonitrile-butadiene rubber,
ethylene propylene rubber, ethylene propylene diene monomer,
polybutadiene rubber, styrene butadiene co-polymer, polyisoprene
rubber, and combinations thereof.
7. The composition as recited in claim 1 wherein the particles are
formed from materials selected from the group consisting of
fluoropolymers, carbon-based materials, furnace carbon black
materials, ground coal materials, graphite materials, boron nitride
materials, mica materials, fiber materials, combinations
thereof.
8. The composition as recited in claim 1 wherein the first
elastomeric material is selected from the group of material
consisting of.fluoropolymers, fluoroelastomers, acrylonitrile
butadiene (nitrile) rubber, highly-saturated nitrile, hydrogenated
nitrile, hydrogenated carboxylated acrylonitrile-butadiene rubber,
ethylene propylene rubber, ethylene propylene diene monomer,
polybutadiene rubber, styrene butadiene co-polymer, polyisoprene
rubber, and combinations thereof
9. The composition as recited in claim 1 wherein the first and
second elastomeric materials are selected from the same general
family of polymeric materials.
10. The composition as recited in claim 4 wherein the family of
polymeric materials is fluoropolymers.
11. The composition as recited in claim 1 further comprising a
filler material that is disposed within the composition and that
has an average size of greater than 100 nm.
12. The composition as recited in claim 1 comprising from about 10
to 90 percent by weight particles based on the total weight of the
particles and the second elastomeric material.
13. The composition as recited in claim 12 comprising from about 12
to 68 percent by weight particles based on the total weight of the
particles and the second elastomeric material.
14. The composition as recited in claim 1 comprising in the range
of from about 20 to 95 percent by weight second elastomeric
material based on the total weight of the composition.
15. The composition as recited in claim 1 comprising in the range
of from about 50 to 90 percent by weight second elastomeric
material based on the total weight of the composition.
16. The composition as recited in claim 1 comprising in the range
of from about 70 to 80 percent by weight second elastomeric
material based on the total weight of the composition.
17. The composition as recited in claim 1 comprising in the range
of from about 0.2 to 65 percent by weight first elastomeric
material based on the total weight of the composition.
18. The composition as recited in claim 1 comprising in the range
of from about 1 to 40 percent by weight first elastomeric material
based on the total weight of the composition.
19. The composition as recited in claim 1 comprising in the range
of from about 2 to 12 percent by weight first elastomeric material
based on the total weight of the composition.
20. The composition as recited in claim 1 comprising a Shore A
hardness at 25.degree. C. of from about 65 to 90, have a modulus of
elasticity at 50 percent elongation in the range of from about 300
to 700 psi, having a modulus of elasticity at 100 percent
elongation in the range of from about 750 to 1,500 psi. and have a
maximum compression set after 25 percent deflection of the original
height for a period of 22 hours at 212.degree. F. of 12
percent.
21. An annular seal ring construction comprising a body and a
sealing surface, wherein the body is formed from an elastomeric
material that is substantially free of particles that are disposed
within a polymer matrix of the elastomeric material, and wherein
the sealing surface is formed from the composition as recited in
claim 1.
22. A composition for making a seal used in a rotary cone bit used
for drilling subterranean formations, the composition comprising: a
first fluoroelastomeric material in the range of from about 0.2 to
65 percent by weight of the total composition; and a second
fluoroelastomeric material in the range of from about 20 to 95
percent by weight of the total composition, the second
fluoroelastomeric material comprising a dispersion of fluoropolymer
particles disposed therein, wherein the particles have an average
size of less than about 100 nm, wherein the composition comprises
in the range of from about 10 to 90 percent by weight of the
particles based on the total weight of the particles and the second
fluoroelastomeric material, and wherein the particles are disposed
within the polymer matrix of the second fluoroelastomeric
material.
23. The composition as recited in claim 22 wherein the first
fluoroelastomeric composition is substantially free of particles
disposed within its polymer matrix.
24. The composition as recited in claim 22 wherein the particles
are formed from polytetrafluoroethylene and have an average
particle size in the range of 30 to 80 nm.
25. The composition as recited in claim 22 further comprising a
solid filler material having an average particle size of greater
than 100 nm.
26. The composition as recited in claim 22 wherein the seal formed
therefrom is in the form of an annular ring having an outer
diameter sealing surface and an inner diameter sealing surface,
wherein the inner and outer diameter sealing surfaces each have a
different radius of curvature.
27. The composition as recited in claim 26 wherein the one of the
inner and outer diameter sealing surfaces is placed into dynamic
sealing operation, and wherein the sealing surface placed into
dynamic sealing operation is formed from the seal composition.
28. A rotary cone bit for drilling subterranean formations
comprising: a bit body having at least one leg, the leg including a
journal pin; a cutter cone rotatably mounted on the leg; and an
annular elastomeric seal ring located between a first sealing
surface on the leg and a second sealing surface on the cutter cone
that forms a dynamic rotary seal between the leg and cutter cone
while the cone is rotating, wherein the seal ring is formed from a
composition comprising: in the range of from about 0.2 to 65
percent by weight of a first elastomeric material based on the
total weight of the composition; and in the range of from bout 10
to 95 percent by weight of a second elastomeric material based on
the total weight of the composition, the second elastomeric
material comprising a dispersion of particles disposed therein
within a polymer matrix of the second elastomeric material, wherein
the particles are formed from a material that is compatible with
the second elastomeric material and have an average size of less
than about 100 nm, and wherein the composition comprises in the
range of from 10 to 90 percent by weight particles based on the
total weight of the second fluoroelastomeric material and
particles.
29. The rotary cone bit as recited in claim 28 wherein the first
and second elastomeric materials are selected form the group
consisting of.fluoropolymers, fluoroelastomers, acrylonitrile
butadiene (nitrile) rubber, highly-saturated nitrile, hydrogenated
nitrile, hydrogenated carboxylated acrylonitrile-butadiene rubber,
ethylene propylene rubber, ethylene propylene diene monomer,
polybutadiene rubber, styrene butadiene co-polymer, polyisoprene
rubber, and combinations thereof
30. The rotary cone bit as recited in claim 28 wherein the first
and second elastomeric materials are fluoroelastomers, and wherein
the particles are formed from a fluoropolymeric material.
31. The rotary cone bit as recited in claim 28 further comprising a
solid filler having an average particle size of greater than 100
nm.
32. The rotary cone bit as recited in claim 28 wherein the seal
ring comprises a dynamic sealing surface formed from the
composition and another region that is formed from an elastomeric
material different than the composition.
33. The rotary cone bit as recited in claim 28 wherein the seal
ring comprises a first sealing surface and a second sealing
surface, wherein each sealing surface has a different surface
configuration.
34. An annular seal for use with within a rotary cone bid for
drilling a subterranean formation, the seal comprising: a
elastomeric body; a first sealing surface positioned along one
portion of the body; and a second sealing surface position along
another portion of the body; wherein at least one of the sealing
surfaces us formed from a composition comprising: a first
elastomeric material; and a second elastomeric material, wherein
the second elastomeric material comprises a dispersion of particles
disposed within a polymer matrix of the less than about 100 nm.
35. The annular seal as recited in claim 34 wherein the first and
second sealing surfaces are each configured having a different
radius of curvature.
Description
FIELD OF THE INVENTION
[0001] This invention relates to seals such as those used with oil
production equipment that comprise an elastomeric composition
specially formulated to include nanoparticles and that provides
improved mechanical properties, fuel resistance, grease resistance,
oil-based mud resistance, temperature resistance and wear
resistance when compared to seals formed from conventional
elastomeric materials.
BACKGROUND OF THE INVENTION
[0002] Seals can be used in a variety of end-use applications. One
demanding end-use application is with oil production equipment,
e.g., such as that used for drilling subterranean formations. An
example of such equipment includes rotary cone drill bits that are
connected to drill string. In use, the drill string and bit body
are rotated in the bore hole where high pressures and temperatures
are encountered.
[0003] The total useful life of a drill bit in such severe
environments is in the order of 20 to 200 hours for bits in sizes
of about 61/2 to 121/4 inch diameter at depths of about 5,000 to
20,000 feet that are operated at about 200 rpm. Useful lifetimes of
about 65 to 150 hours are typical. However, the useful life of
drill bits that are operated at higher revolutions such as 375 rpm,
i.e., high-speed drill bits, is generally in the range of from
about 20 to 50 hours. The shortened useful life is often due to the
increased frictional heat produced in the bit caused by the
increased operating speed.
[0004] When a drill bit wears out or fails as a bore hole is being
drilled, it is necessary to withdraw the drill string for replacing
the bit. The amount of time required to make a round trip for
replacing a bit is essentially lost from the drilling operation.
This time can become a significant portion of the total time for
completing a well, particularly as the well depths become great. It
is therefore quite desirable to maximize the service life of a
drill bit in a rock formation. Prolonging the time of drilling
minimizes the time lost in "round tripping" the drill string for
replacing the bits. Replacement of a drill bit can be required for
a number of reasons, including wearing out or breakage of the
structure contacting the rock formation.
[0005] One reason for replacing the rock bits includes failure or
severe wear of the journal bearings. These bearings are subject to
high pressure drilling loads, high hydrostatic pressures in the
hole being drilled, and high temperatures due to drilling, as well
as elevated temperatures in the formation being drilled.
Considerable development work has been conducted over the years to
produce bearing structures and to employ materials that minimize
wear and failure of such bearings.
[0006] The journal bearings are lubricated with grease adapted to
such severe conditions. Such lubricants are an important element in
the life of a rock bit. Pressure and temperature conditions in a
drill bit can vary with time as the drill bit is used. For example,
when a "joint" of pipe is added to the drill string, weight on the
bit can be relieved and slight flexing can occur. Such variations
can result in "pumping" of the grease through O-ring seals, leading
to loss of grease or introduction of foreign abrasive materials,
such as drilling mud, that can damage bearing surfaces. Bearing
failure can often be traced to failure of the seal that retains
lubricant in the bearing. Lubricant may be lost if the seal fails,
or if abrasive particles of rock work their way into the bearing
surfaces, causing excessive wear.
[0007] Rock bit O-rings are expected to perform in environments
that are extremely harsh. Modern bits are being run at
exceptionally high surface speeds, sometimes more than 500 feet per
minute, with cone speeds averaging in the range of from 200 to 400
revolutions per minute. One face of the O-ring is exposed to
abrasive drilling mud. The life of the O-ring may be significantly
degraded by high temperatures due to friction (as well as elevated
temperature in the well bore) and abrasion.
[0008] It is therefore desired that a seal have a material
construction that is capable of maintaining the lubricant within
oil production equipment, e.g., a drill bit, that has a long useful
life, that is resistant to crude gasoline and other chemical
compositions found within oil wells, that has high heat resistance,
is resistant to abrasion, and that will not readily deform under
load and allow leakage of the grease from within the bit or
drilling mud into the bit, thereby providing a desired improvement
in service life when compared to seals formed from conventional
elastomeric materials.
SUMMARY OF THE INVENTION
[0009] Seals and sealing members prepared according to principles
of this invention are formed from a composition generally
comprising a first elastomeric material and a second elastomeric
material, wherein the second elastomeric material comprises a
dispersion of nanosized particles disposed within a polymer matrix
of the second elastomeric material. In an example embodiment, the
first and second elastomeric materials can be the same or
different, and can be selected from the group of materials
including fluoropolymers, fluoroelastomers, acrylonitrile butadiene
(nitrile) rubber, highly-saturated nitrile, hydrogenated nitrile,
hydrogenated carboxylated acrylonitrile-butadiene rubber, ethylene
propylene rubber, ethylene propylene diene monomer, polybutadiene
rubber, styrene butadiene co-polymer, polyisoprene rubber, and
combinations thereof.
[0010] The nanosized particles have an average particle size of
less than about 100 nm, and can be formed form the group of
materials including fluoropolymers, carbon-based materials, furnace
carbon black materials, ground coal materials, graphite materials,
boron nitride materials, mica materials, fiber materials, and
combinations thereof.
[0011] In an example embodiment the first elastomeric material may
be present n the range of from about 0.2 to 65 percent by weight of
the total composition, and the second elastomeric material present
in the range of from about 20 to 95 percent by weight of the total
composition, and the composition comprises in the range of from
about 10 to 90 percent by weight of the particles based on the
total weight of the particles and the second elastomeric material.
The composition may have a Shore A hardness at 25.degree. C. of
from about 65 to 90, have a modulus of elasticity at 50 percent
elongation in the range of from about 300 to 700 psi, have a
modulus of elasticity at 100 percent elongation in the range of
from about 750 to 1500 psi and have a maximum compression set after
25 percent deflection of the original height for a period of 22
hours at 212.degree. F. of about 12 percent. In an example
embodiment, the composition is used to form an annular seal
disposed within a rotary cone bit for drilling subterranean
formations, wherein the composition can form a specific sealing
surface of the seal, wherein the seal comprises a composite
construction of different materials, or can form the entire seal.
Such seals can be configured as needed to provide a desired sealing
service.
[0012] Seals and seal members formed from such composition display
improved combined properties of modulus, elongation, hardness,
compression set, chemical resistance, wear resistance and
temperature resistance when compared to seal constructions formed
from conventional elastomeric or rubber the comprise conventional
fillers, e.g., fillers that are not nano-particles and that are
simply added to the elastomeric material, i.e., that are not
incorporated during the polymerization stages into the polymer
matrix of the elastomeric material.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] These and other features and advantages will become
appreciated as the same becomes better understood with reference to
the specification, claims and drawings wherein:
[0014] FIG. 1 is a semi-schematic perspective view of a rotary cone
drill bit containing a seal constructed according to the principles
of this invention;
[0015] FIG. 2 is a partial cross-sectional view of the rotary cone
drill bit of FIG. 1;
[0016] FIG. 3 is a perspective view of one embodiment of a seal
constructed according to principles of this invention;
[0017] FIG. 4 is a cross-sectional view of the seal of FIG. 3;
[0018] FIG. 5 is a cross-sectional view of another seal
embodiment;
[0019] FIG. 6 is a cross-sectional view of another seal
embodiment;
[0020] FIG. 7 is a cross-sectional view of another seal embodiment;
and
[0021] FIG. 8 is a cross-sectional view of another seal
embodiment.
DETAILED DESCRIPTION
[0022] Seals or sealing members formed according to principles of
the invention are useful in applications such as in oil production
equipment and comprise an elastomeric material composition that has
been specially engineered to include nanoparticles dispersed within
the polymer matrix of one or more elastomeric materials. In an
example embodiment, a volume of nanoparticles formed from a
selected group of materials are dispersed within the polymer matrix
of a selected host elastomeric material. In an example embodiment,
the nanoparticles are introduced or otherwise provided within the
host elastomeric material prior to or during the polymerization of
the host elastomeric material such that upon the polymerization of
the host elastomeric material the nanoparticles are disposed within
the polymer matrix of the resulting elastomeric material.
[0023] Seals and seal members comprising such elastomeric
composition can be used in a variety of different end-use
conventional oil production sealing applications. In an example
sealing application, the seal or sealing member is provided in the
form of an annular seal ring or an O-ring seal. Such O-ring seals
can be used for example within a rotary cone drill bit or rock bit
that is used for drilling subterranean formations.
[0024] FIG. 1 illustrates an example rotary cone drill bit or rock
bit 10 comprising a body 12 having a number of cutter cones 14,
e.g., three cutter cones, each rotatably mounted on respective legs
13 that extend along a lower end of the body 12. A threaded pin 16
is at the upper end of the body for assembly of the rock bit onto a
drill string for drilling oil wells or the like. A plurality of
cutting inserts 18 are attached to the cutter cones for bearing on
the subterranean formation being drilled. Nozzles 20 in the bit
body introduce drilling mud into the space around the cutter cones
for cooling and carrying away formation chips drilled by the
bit.
[0025] O-ring seals are generally thought of as comprising a
cylindrical inside and outside diameter, and a cylindrical cross
section. Accordingly, for purposes of reference and clarity, the
figures used to describe principles and embodiments of this
invention have been created to illustrate an annular seal ring. It
is to be understood that the principles of this invention are meant
to apply to other sealing members that may not be in the form of an
annular ring, and to annular seal rings that may have a symmetric
or asymmetric cross sectional configuration. Therefore, it is to be
understood that the principles of this invention may apply to
annular ring seals or O-rings configured having a circular,
non-circular, symmetric, or asymmetric cross sectional
configurations.
[0026] FIG. 2 is a fragmentary, longitudinal cross-section of the
rock bit, extending radially from the rotational axis 22 of the
rock bit through one of the three legs on which the cutter cones 14
are mounted. Each leg 13 includes a journal pin 24 extending
downwardly and radially, inwardly on the rock bit body. The journal
pin includes a cylindrical bearing surface having a hard metal
insert 26 on a lower portion of the journal pin. The hard metal
insert is typically a cobalt or iron-based alloy welded in place in
a groove on the journal leg and having a substantially greater
hardness that the steel forming the journal pin and rock bit
body.
[0027] An open groove 28 is provided on the upper portion of the
journal pin. Such a groove may, for example, extend around 60
percent or so of the circumference of the journal pin, and the hard
metal insert 26 can extend around the remaining 40 percent or so.
The journal pin also has a cylindrical nose 30 at its lower
end.
[0028] Each cutter cone 14 is in the form of a hollow,
generally-conical steel body having cutting inserts 18 pressed into
holes on the external surface. The inserts may be formed from a
cermet material, such as cemented tungsten carbide or the like, and
may comprise a working surface comprising an ultra-hard material
such as polycrystalline diamond, polycrystalline cubic boron
nitride, or the like. The cutting inserts provide the drilling
action by engaging a subterranean rock formation as the rock bit is
rotated. Some types of bits have hard-faced steel teeth milled on
the outside of the cone instead of cutting inserts.
[0029] The cavity in the cone contains a cylindrical bearing
surface including an aluminum bronze insert 32 deposited in a
groove in the steel of the cone or as a floating insert in a groove
in the cone. The aluminum bronze insert 32 in the cone engages the
hard metal insert 26 on the leg and provides the main bearing
surface for the cone on the bit body. A nose button 34 is between
the end of the cavity in the cone and the nose 30 and carries the
principal thrust loads of the cone on the journal pin. A bushing 36
surrounds the nose and provides additional bearing surface between
the cone and journal pin. Other types of bits, particularly for
higher rotational speed applications, have roller bearings instead
of the exemplary journal bearings illustrated herein. It is to be
understood that seals constructed according to principles of this
invention may be used with rock bits comprising either roller
bearings or conventional journal bearings.
[0030] A plurality of bearing balls 38 are fitted into
complementary ball races in the cone and on the journal pin. These
balls are inserted through a ball passage 40, which extends through
the journal pin between the bearing races and the exterior of the
rock bit. A cone is first fitted on the journal pin, and then the
bearing balls 38 are inserted through the ball passage. The balls
carry any thrust loads tending to remove the cone from the journal
pin and thereby retain the cone on the journal pin. The balls are
retained in the races by a ball retainer 42 inserted through the
ball passage 40 after the balls are in place. A plug 44 is then
welded into the end of the ball passage to keep the ball retainer
in place.
[0031] The bearing surfaces between the journal pin and the cone
are lubricated by a grease material. Preferably, the interior of
the rock bit is evacuated, and grease is introduced through a fill
passage (not shown). The grease thus fills the regions adjacent the
bearing surfaces plus various passages and a grease reservoir, and
air is essentially excluded from the interior of the rock bit. The
grease reservoir comprises a cavity 46 in the rock bit body, which
is connected to the ball passage 40 by a lubricant passage 48.
Grease also fills the portion of the ball passage adjacent the ball
retainer, the open groove 28 on the upper side of the journal pin,
and a diagonally extending passage 50 there between. Grease is
retained in the bearing structure by a resilient seal in the form
of an O-ring 52 disposed between the cone and journal pin.
Preferably, the O-ring seal is disposed in a slightly V-shaped
groove.
[0032] A pressure compensation subassembly is included in the
grease reservoir 46. The subassembly comprises a metal cup 54 with
an opening 56 at its inner end. A flexible rubber bellows 58
extends into the cup from its outer end. The bellows is held into
place by a cap 60 with a vent passage 62. The pressure compensation
subassembly is held in the grease reservoir by a snap ring 64 or
the like.
[0033] When the rock bit is filled with grease, the bearings, the
groove 28 on the journal pin, passages in the journal pin, the
lubrication passage 48, and the grease reservoir on the outside of
the bellows 58 are filled with grease. If the volume of grease
expands due to heating, for example, the bellows 58 are contracted
to provide additional volume in the sealed grease system, thereby
preventing accumulation of excessive pressures. High pressure in
the grease system can damage the O-ring seal 52 and permit drilling
mud or the like to enter the bearings. Such material is abrasive
and can quickly damage the bearings. Conversely, if the grease
volume should contract, the bellows can expand to prevent low
pressures in the sealed grease system, which could cause flow of
abrasive and/or corrosive substances past the O-ring seal.
[0034] The bellows has a boss 66 at its inner end which can seat
against the cap 60 at one end of the displacement of the bellows
for sealing the vent passage 62. The end of the bellows can also
seat against the cup 54 at the other end of its stroke, thereby
sealing the opening 56. If desired, a pressure relief check valve
can also be provided in the grease reservoir for relieving
over-pressures in the grease system that could damage the O-ring
seal. Even with a pressure compensator, it is believed that
occasional differential pressures may exist across the O-ring seal
of up to .+-.150 psi.
[0035] To maintain the desired performance of the O-ring seal at
the pressure and temperature conditions that prevail in a rock bit,
to inhibit "pumping" of the grease through the O-ring seal, and for
a long useful service life, it is important that the O-ring seal be
resistant to crude gasoline and other chemical compositions found
within oil wells, have a high heat and abrasion resistance, have
low rubbing friction, and not be readily deformed under the
pressure and temperature conditions in a well which could allow
leakage of the grease from within the bit or drilling mud into the
bit.
[0036] Therefore, it is desired that the O-ring seal have a modulus
of elasticity at 100 percent elongation of from about 850 to 1275
psi, a minimum tensile strength of about 2300 psi, elongation of
from about 200 to 350 percent, a die C tear strength of at least
about 250 lb/in., a durometer hardness Shore A in the range of from
about 75 to 85, and a compression set after about 70 hours at
100.degree. C. of less than about 18 percent and preferably less
than about 16 percent.
[0037] Conventional seals used in oil production applications such
as drill bits have been formed from a variety of different
materials. Such seals conventionally comprise acrylonitrile
polymers or acrylonitrile/butadiene copolymers. Other components in
the polymers are activators or accelerators for curing the polymer,
such as stearic acid, and agents that can contribute to the heat
resistance of the polymer, such as zinc oxide and curing agents.
However, these synthetic rubbers typically exhibit poor heat
resistance and become brittle at elevated temperatures after
extended periods of time. Additionally, such compounds are known to
provide a low degree of chemical resistance, and often exhibit
undesirably low tensile strength and high coefficients of friction.
Such properties are undesirable for a seal in a drill bit
application, since the high operating temperatures of the bit can
result in early seal failure, thereby reducing the effective drill
bit service life.
[0038] Seals and sealing members of the present invention are
specially formulated/engineered to include nanoparticles that are
dispersed within the polymer matrix of one or more elastomeric
materials. The elastomeric material and the nanoparticles are
specifically selected to produce a seal composition that will
provide a seal construction having desired improvements in
performance characteristics to thereby extended seal service life
when compared to seals formed from conventional compositions,
thereby operating to extend the effective service life of the drill
bit or other device comprising the same.
[0039] In an example embodiment, the seal comprises an elastomeric
material having a desired volume of nanoparticles dispersed
therein. More specifically, the nanoparticles are dispersed within
a substantially continuous polymer matrix forming the elastomeric
material. Such elastomeric material can be referred to the
nanoparticle "host" elastomeric material for this reason. In such
example embodiment, it is desired that the nanoparticles be
dispersed substantially uniformly throughout the polymer matrix
forming the elastomeric material. In such embodiment, the
nanoparticles can be thought of as a plurality of cores that are
each surrounded by a shell formed from the continuous polymer
matrix of the elastomeric material. Thus, a feature of such
embodiment is the introduction/incorporation and existence of the
nanoparticles within the actual polymer matrix or polymer framework
of the elastomeric material. In an example embodiment, such
introduction can be achieved by introducing the nanoparticles into
a precursor elastomeric material at a time before it is polymerized
and then subsequently commencing the desired polymerization to form
the elastomeric material.
[0040] Elastomeric materials useful for forming the nanoparticle
host can be selected from the group including but not limited to
fluoropolymers, fluoroelastomers, acrylonitrile butadiene (nitrile)
rubber, highly-saturated nitrile, hydrogenated nitrile,
hydrogenated carboxylated acrylonitrile-butadiene rubber, ethylene
propylene rubber, ethylene propylene diene monomer, polybutadiene
rubber, styrene butadiene co-polymer, polyisoprene rubber,
combinations thereof, and the like. Functionally, it is desired
that the nanoparticle host elastomeric material be selected from
those materials capable of accommodating the introduction/placement
of the nanoparticles dispersion within the polymer matrix during
polymerization of the host material. It is also desired that such
elastomeric material have desired properties of elongation,
modulus, hardness, chemical resistance, and temperature resistance
as noted above. It is further desired that the material selected to
form the host elastomeric material be compatible with the
nanoparticle material that is selected.
[0041] The particular choice of host elastomeric material that is
used may depend on such factors as the type of material used to
form the nanoparticles, the particular end-use application, and any
other materials (elastomeric or nonelastomeric) that may be used to
form the seal. For example, it may be desired to form a seal using
two or more different elastomeric materials, where the
nanoparticles are disposed within the polymer matrix of one or more
of the elastomeric materials.
[0042] In an example embodiment, the nanoparticle host elastomeric
material is selected from the group including fluorocarbon,
fluoroelastomer, and/or perfluoroelastomer materials, which can
include copolymers and terpolymers, and combinations thereof. The
use of such fluoroelastomer material is desired for example when
the nanoparticles are formed from or have a fluoropolymer
constituent. Suitable fluoroelastomer materials include but are not
limited to those formed from vinylidene fluoride,
hexafluoropropylene, and tetrafluoroethylene. Such fluoroelastomer
materials display properties of high-temperature stability,
low-temperature toughness and flexibility, low coefficient of
friction, wear resistance and good chemical resistance. In a
preferred embodiment, the fluoroelastomer material contains one or
more of vinylidenefluoride, hexafluoropropylene,
tetrafluoroethylene, and includes a cure site monomer.
[0043] Seals, prepared according to principals of the invention,
can be formulated to comprise the host elastomeric material with
the desired nanoparticles disposed therein, wherein such host
elastomeric material is the only elastomeric material that is used
to make the seal composition. Alternatively, seals can be
formulated with the nanoparticle host elastomeric material
comprising one of one or more other elastomeric materials. Thus,
depending on the particular seal composition embodiment, the host
elastomeric material may comprise 100 percent by weight of the
total weight of the elastomer material used to form the same, or
may comprise some lesser fractional amount depending on the
particular seal formulation.
[0044] In an example embodiment, where the seal is formed using
more than one elastomeric material, the nanoparticle host
elastomeric material is present in the range of from about 20 to 95
percent by weight of the total composition, preferably in the range
of from about 50 to 90 percent by weight of the total composition,
and more preferably in the range of from about 70 to 80 percent by
weight of the total composition. Generally, it is desired that the
seal composition comprise about 95 percent or less of the host
elastomeric so that sufficient amounts of other materials, such as
curative agents, cure activator, processing aid, and the like are
present. A seal composition comprising less than about 20 percent
by weight of the host elastomeric material may not introduce a
sufficient amount of the nanoparticle material into the formulation
to produce a seal composition having the desired combination of
performance properties necessary to meet the demands of a
particular end-use application.
[0045] While particular amounts of the nanoparticle host
elastomeric material have been disclosed, it is to be understood
that the actual amounts of such material used to make a seal
formulation will depend on a number of different factors such as
the type of nanoparticle host elastomeric material that is used,
the type and/or amount of the nanoparticle material that is used,
the type and/or amount of other elastomeric and/or nonelastomeric
materials that are used, the particular seal configuration, the
particular seal construction, e.g., whether the seal composition
made from such formulation is used to make the entire seal or just
a portion or segment of the same, and the end-use application.
[0046] The materials used to form the nanoparticles can be selected
from the group including but not limited to fluoropolymers,
hydrocarbon-based materials, carbon black materials, ground coal
materials, graphite materials, boron nitride materials, mica
materials, fiber materials, silica materials, clay materials,
combinations thereof, and the like. Preferred materials useful for
forming the nanoparticles include those that are first capable of
forming nano-sized particles. It is further desired that the
material used to form the nanoparticles contribute one or more
properties of hardness, modulus, elongation, temperature
resistance, chemical resistance and the like to the seal
construction. It is further desired that the material selected to
form the nanoparticles be compatible with the host elastomeric
material, and not adversely impact properties and/or performance
characteristics of such host elastomeric material once it is
polymerized. In a preferred embodiment, it is desired that the
material selected to form the nanoparticles be one that compliments
and/or operates to stabilize or otherwise enhance the hosting
environment provided by the elastomeric material, e.g., that
operates to stabilize or strengthen the hosting polymer matrix.
[0047] In an example embodiment, e.g., where the host elastomeric
material selected is a fluoroelastomeric material, a desired
material useful for forming the nanoparticles is a fluoropolymer
material. Fluoropolymer materials useful in this regard include
those characterized as being semi-crystalline, and include but are
not limited to polytetrafluoroethylene, copolymers of
tetrafluoroethylene with co-monomers such as
perfluoromethylvinylether, perfluoropropylvinylether, and
hexafluoropropene, and combinations thereof. A preferred
fluoropolymer material useful for forming the nanoparticles is
polytetrafluoroethylene.
[0048] The particular choice of material used to form the
nanoparticles may depend on such factors as the type of host
elastomeric material that is used, the particular end-use
application, and any other materials (elastomeric or
nonelastomeric) that may be used to form the seal composition.
[0049] A noted feature of the nanoparticles is that they have an
average size of less than about 100 nm, and greater than about 25
nm. In an example embodiment, the nanoparticles have an average
particle size in the range of from about 30 to 80 nm, and more
preferably in the range of from about 35 to 55 nm. Using
nanoparticles having an average particle size greater than about
100 nm may not be desired because the mechanical properties of the
resulting elastomer material comprising the same may be
considerably lower than what is useful for a particular end-use
application, such as a seal within a drill bit. While the use of
nanoparticles having an average size of greater than about 25 nm
has been disclosed, it is possible that nanoparticles sized smaller
that about 25 nm can be used.
[0050] In an example embodiment, where the seal is formed using
more than one elastomeric material, e.g., using the nanoparticle
host elastomeric material and one or more other elastomeric
material, the nanoparticles are present in the range of from about
10 to 90 percent by weight of the combined weight of the
nanoparticle and host elastomeric material, preferably in the range
of from about 12 to 68 percent by weight of the combined weight of
the nanoparticle and host elastomeric material, and more preferably
in the range of from about 15 to 52 percent by weight of the
combined weight of the nanoparticle and host elastomeric material.
A seal composition comprising greater than about 90 percent by
weight of the nanoparticles in the combined nanoparticle and host
elastomeric material may not have sufficient amount of curative
agent, cure activator, processing aid, and the like to form a
composition having the desired performance properties. A seal
composition comprising less than about 10 percent by weight of the
nanoparticles in the combined nanoparticle and host elastomeric
material may not provide a sufficient amount of the nanoparticle
material to produce a seal composition having the desired
combination of performance properties noted above to meet the
demands of a particular end-use application.
[0051] While particular amounts of the nanoparticle material have
been disclosed, it is to be understood that the actual amounts of
such material used to make a seal formulation will depend on a
number of different factors such as the type of nanoparticle
material, the type and/or amount of the host elastomeric material
that is used, the type and/or amount of other elastomeric and/or
nonelastomeric materials that are used, the particular seal
configuration, the particular seal construction, e.g., whether the
seal composition made from such formulation is used to make the
entire seal or just a portion or segment of the same, and the
end-use application.
[0052] As noted above, seals prepared according to principles of
this invention can comprise one or more elastomeric materials. In
an example embodiment, the seal comprises one or more elastomeric
material in addition to the nanoparticle host elastomeric material.
In such embodiment, the nanoparticles are present in the polymer
matrix of the hosting elastomeric material, and the hosting
elastomeric material is combined with the one or more other
elastomeric materials to produce a seal composition that ultimately
provides the desired seal performance properties.
[0053] Such other elastomeric materials may or may not be ones that
are already polymerized before introduction of the nanoparticle
host elastomeric material, i.e., the elastomeric material
containing the nanoparticles. Thus, depending on the desired
formulation and performance properties, the resulting seal
composition may be one that includes the nanoparticles in the
polymer matrix of one or more of the elastomeric materials, or
where the nanoparticles are contained in the polymer matrix of only
the host elastomeric material and not in the polymer matrix of
other elastomer materials.
[0054] Such additional elastomeric materials useful for combining
with the nanoparticle host elastomeric material can be selected
from the materials including but not limited to fluoropolymers,
fluoroelastomers, acrylonitrile butadiene (nitrile) rubber,
highly-saturated nitrile, hydrogenated nitrile rubber, hydrogenated
carboxylated acrylonitrile-butadiene rubber, ethylene propylene
rubber, ethylene propylene diene monomer, polybutadiene rubber,
styrene butadiene co-polymer, polyisoprene rubber, combinations
thereof, and the like. Functionally, it is desired that such
additional elastomeric material be selected from those materials
that are both compatible with the nanoparticle host elastomeric
material, and capable of contributing desired properties of
elongation, modulus, hardness, temperature resistance, and chemical
resistance as noted above to the resulting composition.
[0055] The particular choice of such additional elastomeric
material that is used may depend on such factors as the type of
nanoparticle host elastomeric material that is used, the particular
end use application, any other materials (additives, modifiers,
nonelastomeric materials or the like) that may be used to form the
seal. In an example embodiment, e.g., where the nanoparticle host
elastomeric material that is used is a fluoropolymer material, the
additional elastomeric material is preferably a material that is
compatible with the same.
[0056] In such example embodiment, the additional elastomeric
material can be selected from the group of fluorocarbon,
fluoroelastomer and/or perfluoroelastomer materials, which can
include copolymers and terpolymers. Suitable fluoroelastomer
materials include but are not limited to those formed from
vinylidene fluoride, hexafluoropropylene, tetrafluoroethylene, and
combinations thereof. Such fluoroelastomer materials display
desired properties of high-temperature stability, low-temperature
toughness and flexibility, low coefficient of friction, wear
resistance and good chemical resistance. In a preferred embodiment,
the fluoroelastomer is the same type as that used to form the
nanoparticle host elastomeric material
[0057] In an example embodiment, where the seal is formed using one
or more additional elastomeric materials, such additional
elastomeric material is present in the range of from about 0.2 to
65 percent by weight of the total composition, preferably in the
range of from about 1 to 40 percent by weight of the total
composition, and more preferably in the range of from about 2 to 12
percent by weight of the total composition. A seal composition
comprising greater than about 65 percent by weight of such
additional elastomeric material may limit the ability to provide a
desired amount of nanoparticle elastomeric host material in the
final compound. While a lower limit of about 0.2 percent by weight
of the additional elastomeric material has been disclosed, there
may be situations where less about that 0.2 percent by weight of an
additional elastomeric material may be useful.
[0058] While particular amounts of an additional elastomeric
material have been disclosed, it is to be understood that the
actual amounts of such material used to make a seal formulation
will depend on a number of different factors such as the type of
nanoparticle hosting elastomeric material that is used, the type
and/or amount of the nanoparticle material that is used, the type
and/or amount of other materials such as modifiers, curing agents,
and/or nonelastomeric materials that are used, the particular seal
configuration, the particular seal construction, e.g., whether the
seal composition made from such formulation is used to make the
entire seal or just a portion or segment of the same, and the
end-use application.
[0059] In addition to those materials described above, compositions
useful for making seals according to principles of the invention
can include other materials such as flow modifiers, curing agents,
pigments and coloring agents, and the like.
[0060] Flow modifiers and processing agents can be used to control
one or more features of the composition during mixing, extruding,
calendaring, fabricating, curing, and/or molding, e.g., controlling
the viscosity of the composition, reduce unwanted foaming and the
like. Such modifiers and processing agents useful in this regard
include those that are used for making conventional seal
compositions, e.g., from conventional rubber materials. The amount
of any such modifiers or agents used to make seals according to the
principles of this invention can and will vary depending on a
variety of factors. In the event that modifiers and/or processing
agents are used they may be present up to about 5 percent by weight
based on the weight of the total composition.
[0061] Cross linking agents often referred as curing agents are
used to create cross-links between the polymer chains of
elastomeric materials. Curing agents are employed to cross-link or
cure the nanoparticle containing polymer host material. Curing
agents useful in this respect include those that conventionally
used for curing the selected elastomeric materials and/or
nanoparticle material. In an example embodiment, useful curing
agents include peroxides, bisphenol, or amines. In the event that
curing agents are used, such curing agents can be present up to
about 8 percent by weight based on the weight of the total
composition.
[0062] Pigments and/or coloring agents can be used to provide a
seal composition having a desired color or appearance. Pigments
and/or coloring agents useful in this respect include those
conventionally used for the purpose of coloring elastomeric seal
compositions. In the event that pigments and/or coloring agents are
used, such pigments and/or coloring agents can be present up to
about 5 percent by weight based on the weight of the total
composition
[0063] Fillers in addition to the nanoparticles described above can
additionally be used to form seal compositions according to
principals of the invention. Such fillers can be added to improve
the hardness or rigidity of the seal and/or to reduce the surface
friction of the seal. Fillers useful in this respect include those
noted above useful for forming the nanoparticle material. If
desired, such fillers can be provided in the form of particles,
fibers, fabric, and the like. The use of such additional materials
can and will vary depending on the nature of the seal composition
and, the end-use application, and the desired performance
properties. Such additional filling materials or fillers can be
added to the host or other elastomeric materials, and may or may
not be disposed within the polymer matrix of such elastomeric
materials. In an example embodiment, such additional fillers or
solids have a particle size of greater than about 100 nm and are
combined with the elastomeric materials after they have been
polymerized.
[0064] Low friction fillers can be used and may include soft
metallic materials such as copper, bronze, brass and the like, or
hard metallic materials such as nickel, cobalt or the like, or
ceramic-metal composite materials such as cemented tungsten
carbide, titanium carbide and the like, or may include ceramic
materials such as cubic or spherical boron nitride, diamond,
diamond-like graphite, silicon carbide and the like. Additionally,
such fillers can be provided in the form of fibers and/or fabric
formed from fibers. Such fibers can be formed from synthetic or
natural materials, and can be sized in length and diameter to
provide a desired performance property. In the event that fillers
are used, such fillers can be present up to about 20 percent by
weight based on the weight of the total composition.
[0065] Seals and sealing members constructed in accordance with
principles of the invention may be configured differently as called
for by the particular end-use applications. As noted above, for use
as a seal in a rotary cone drill bit it is desired that the seal be
configured in the form of an annular ring or O-ring.
[0066] FIGS. 3 and 4 illustrate an example embodiment of a seal 70,
formed according to principles of the invention, having an annular
ring-shaped body 72. In this particular embodiment, the seal 70
includes an outer diameter sealing surface 74 and an inner diameter
sealing surface 76, wherein the outer diameter sealing surface has
a radius of curvature that is different from that of the inner
diameter sealing surface. In this particular embodiment, the outer
diameter sealing surface has a radius of curvature that is less
than that of the inner diameter sealing surface. The outer diameter
sealing surface 74 is configured to provide a desired seal against
a stationary sealing surface of the cone and to provide a desired
energizing function, while the inner diameter sealing surface 76 is
configured to provide a desired seal against a dynamic sealing
surface of the bit body.
[0067] The example seal 70 is formed from two different materials;
namely a first seal material 78 forming the outer sealing surface
74 and a portion of the seal body, and a second seal material 80
forming the inner sealing surface 76. Thus, the elastomeric
nanoparticle seal composition prepared according to principles of
this invention can be used to form one or both of the first and
second seal materials. In a preferred embodiment, the elastomeric
nanoparticle seal composition is used to form the portion of the
seal comprising the dynamic sealing surface 76. In this particular
embodiment, the first seal material 78 is formed from a material
that will operate to provide an energizing function to the seal
body, while the second seal material 80 comprises the nanoparticles
to provide the desired performance properties noted above at the
dynamic sealing surface, e.g., along the inner diameter, where
properties of heat resistance and wear resistance are most
needed.
[0068] FIG. 5 illustrates an alternative embodiment of a seal 82
having the same general configuration as that illustrated in FIGS.
3 and 4, but where the seal is formed from three different
materials; namely a first material 84 used to form an outer
diameter sealing surface 86, a second material 88 used to form an
inner diameter sealing surface 90, and a third material 92 used to
form an inner seal body portion that is interposed between the
inner and outer sealing surfaces. The elastomeric nanoparticle seal
composition can be used to form any one or more of these seal
regions. In an example embodiment, the elastomeric nanoparticle
seal composition is used to form to provide the desired performance
properties noted above at the dynamic sealing surface, e.g., along
the inner diameter, where properties of heat resistance and wear
resistance are most needed.
[0069] While not specifically illustrated, it is to be understood
that the seal embodiment illustrated in FIGS. 3 to 5, having the
differently configured inner and outer sealing surfaces, can be
formed from a single-type of elastomeric material, and that
material can be the elastomeric nanoparticle material disclosed
above.
[0070] FIG. 6 illustrates a further example embodiment of a seal
94, formed according to principals of the invention, having an
annular ring-shaped body 95. In this particular embodiment, the
seal body has a circular cross-sectional configuration with outer
and inner diameter sealing surfaces 96 and 98 having the same
radius of curvature. Additionally, in this particular embodiment
the seal body and both sealing surfaces are all formed from the
same elastomeric material; namely, the elastomeric nanoparticle
material disclosed above.
[0071] FIG. 7 illustrates an alternative embodiment of a seal 102
that is similar to that illustrated in FIG. 6 in that it has a
generally circular cross-sectional configuration. However, the seal
102 comprises an inside diameter sealing surface 104 that is formed
from a material 106 different from a material 108 used to form the
seal body 110 and an outer diameter sealing surface 112. Like the
embodiment illustrated in FIG. 4, the elastomeric nanoparticle seal
composition can be used to form any portion of this seal, and in a
preferred embodiment is used to provide the desired performance
properties noted above at the dynamic sealing surface, e.g., along
the inner diameter, where properties of heat resistance and wear
resistance are most needed.
[0072] FIG. 8 illustrates another alternative embodiment of a seal
114 that is similar to that illustrated in FIG. 6 in that it has a
generally circular cross-sectional configuration. However, the seal
114 is formed using three different materials, namely, a first
material 116 that is used to form an outer diameter sealing surface
118, a second material 120 that is used to form an inner diameter
sealing surface 122, and a third material 124 that is used to form
a remaining portion of the seal body 126 interposed between the
inner and outer diameter sealing surfaces. Like the embodiment
illustrated in FIG. 5, the elastomeric nanoparticle seal
composition can be used to form any portion of this seal, and in a
preferred embodiment is used to provide the desired performance
properties noted above at the dynamic sealing surface, e.g., along
the inner diameter, where properties of heat resistance and wear
resistance are most needed.
[0073] Thus, it is to be understood that elastomeric nanoparticle
seal compositions of this invention can be used to form all or part
of a seal or seal member depending on the particular seal
configuration and the end-use seal application. Additionally, for
those seal constructions comprising more than one seal composition
or seal material, elastomeric nanoparticle seal compositions of
this invention can be used to form such different regions or
portions of the seal where the formulation of the elastomeric
nanoparticle composition in each such region may be different to
provide the particular performance properties called for by the
respective different regions. Thus, even though seal constructions
may comprise more than one type of seal material it is to be
understood that the elastomeric nanoparticle seal compositions of
this invention can be formulated for use as or more of the seal
materials used to make the seal construction.
[0074] Further, FIGS. 3 to 8 illustrate example seals having
particular configurations. It is to be understood that such
illustrated configurations are provided for purposes of reference
and that seal compositions according to principles of this
invention are intended and understood to be used to make
differently configured seals in addition to those specifically
illustrated. Accordingly, it is to be understood that seal
constructions comprising compositions described above can be
configured differently to meet particular end-use applications and
such differently configured seal constructions are understood to be
within the scope of the invention.
[0075] Seals compositions and constructions formed according to
principles of the invention may be better understood with reference
to the following example.
[0076] A seal composition is prepared by polymerizing a
fluoropolymer in the form of polytetrafluoroethylene in a reactor
to obtain a desired nanometric latex size. Subsequently, the
polytetraefluoroethylene latex is used as a seed and polymerization
of a host elastomeric material in the form of a fluoroelastomer
material is commenced. Upon completing the host elastomeric
material polymerization, the resulting composition comprises a
dispersion of nanoparticles formed from polytetrafluoroethylene in
the polymeric matrix of the fluoroelastomeric material. The weight
percentage of the nanoparticles within the host fluoroelastomeric
material is within the ranges disclosed above. The nanoparticle
containing fluoroelastomeric material is then combined with a
further elastomeric material and any processing promoters, flow
modifiers, curing agents, pigments and/or coloring agents, and/or
additional fillers in the weight percentages disclosed above, and
these materials are mixed together so that the nanoparticles and
any additional fillers are substantially uniformly distributed. The
resulting composition is either compression, transfer, or injection
molded into a desired shape to form all or part of the seal.
[0077] In the above-noted example embodiment, the resulting seal
composition comprised: approximately 37 percent by weight of the
nanoparticles and host elastomeric material (e.g., one that is
available under the product name Tecnoflon P959/30M from Solvey
Solexis), where the nanoparticles comprise approximately 11 percent
by weight of the total weight of the nanoparticles and the host
elastomeric material; approximately 39 percent by weight of another
elastomeric material (a fluoroelastomeric material that is
available under the product name Tecnoflon P959); approximately 1.0
percent by weight of processing aid (one that is available under
the product name Tecnoflon FPA 1); approximately 19 percent by
weight of filler (one that is available under the product name
Medium Thermal Black, ASTM designation N-990); approximately 3
percent by weight of cure promoter (Triallyl isocyanurate that is
available under the product name TAIC DLC-A (Triallyl isocyanurate
on silicon dioxide) from Natrochem, Inc.); and approximately 1.0
percent by weight of peroxide curing agent
(2,5-dimethyl-2,5-di(tert-butylperoxy)hexane available under the
product name VAROX DBPH-50 from R.T. Vanderbilt Company, Inc.).
[0078] Seals produced in the noted example displayed significantly
improved overall physical properties such as higher modulus at
lower strain levels, improved wear resistance (in some cases
improved by 300 percent), low compression set and low stress
relaxation for better sealability, improved high temperature
properties, excellent resistance to greases, oils and fluids, when
compared to seals produced from conventional materials not
including the nanoparticles.
[0079] A feature of seals constructions formed from the
compositions described above is that they display improved combined
properties of modulus, elongation, hardness, compression set,
chemical resistance, and temperature resistance when compared to
seal constructions formed using conventional elastomeric or rubber
materials. Such combination of performance properties were not
before possible using conventional elastomeric or rubber materials
that comprise conventional fillers, e.g., fillers that are simply
added to the elastomeric material and that are not incorporated
into the polymer having such improved combined performance
properties is desired for the purpose of extending the service life
of a end-use device, e.g., a rotary cone drill bit, that includes
the same, thereby reducing operating expenses associated operating
the end-use device and conducting the end-use application, e.g.,
drilling a subterranean formation.
[0080] Although, limited embodiments of seal and seal member
constructions and compositions used to form the same have been
described and illustrated herein, many modifications and variations
will be apparent to those skilled in the art. Accordingly, it is to
be understood that within the scope of the appended claims, that
seal constructions and compositions used to form the same according
to principles of this invention may be embodied other than as
specifically described herein.
* * * * *